[Math] Number of songs sung.

arithmeticpuzzle

There were 750 people when the first song was sung. After each song, 50 people are leaving the hall. How many songs are sung to make them zero?

The answer is 16, I am unable to understand it. I am getting 15 as the answer. Please explain.

Best Answer

I wrote it all out to make sure that I wasn't missing a song, but I got 15 too. My best guess is that the question is not worded well, and by "when the first song was sung," they are implying that 750 people were still there at the end of the first song and people started leaving "after each [following] song". This would make the following result:

After 1 song - 750 people remaining
2 songs - 700 people remaining
3 - 650
4 - 600
5 - 550
6 - 500
7 - 450
8 - 400
9 - 350
10 - 300
11 - 250
12 - 200
13 - 150
14 - 100
15 - 50
16 - 0

So this would be ((750 people) - (50 people per song)*(n-1 songs)), but this is contingent on the assumption that nobody left after the first song.

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